Suture anchors are commonly used in surgery to fix soft tissues, such as ligaments and tendons, to bone. The anchor component, which is inserted into bone, may be made from metal or a polymer, and is typically implanted into a pre-drilled hole. Anchor designs in current use include those that screw into the bone, and molded parts that engage with the bone using an interference fit. The anchor design normally includes an eyelet, for example, a hole or a loop in the anchor, through which the suture can be passed, to allow attachment of the suture to the anchor. The suture may be made from a non-absorbable material or an absorbable material, and may also be a monofilament, braid or combinations thereof. Once the anchor has been inserted into the bone, the suture can be used to fix soft tissue to the bone.
U.S. Pat. No. 6,838,493 to Williams et al., for example, discloses suture anchors made from resorbable polyhydroxyalkanoates and other materials, including poly-4-hydroxybutyrate, wherein the anchor component is a rigid molded part that either screws into the bone or engages using an interference fit.
Very recently, soft suture anchors have been developed, for example, the Biomet JUGGERKNOT™, Stryker ICONIX™, ConMed LINVATEC® Y-knot, and Smith & Nephew SUTUREFIX ULTRA® devices, to eliminate concerns with existing suture anchor technology. During deployment, these soft suture anchors are inserted into pre-drilled pilot holes, the suture anchor mechanisms are released, and the anchors are fixed securely in the bone holes.
Various designs have been used to secure soft suture anchors in bone, including expansion of braided suture, vertical contraction and lateral expansion of suture tapes, and the use of a sheath that bunches inside the bone hole causing targeted compression. US Patent Application No. 2011/0098727 to Kaiser et al. discloses a flexible anchor made from a braided or woven fabric with two openings positioned between the first and second ends of the flexible anchor such that one end of a suture can be passed inside the first opening of the flexible anchor, along a passageway inside the flexible anchor, and out of the second opening in the flexible anchor. The ends of the suture can be held so that the flexible anchor forms substantially a U-shape for insertion, with the ends of the flexible anchor forming legs or tail portions that can provide additional resistance when the anchor is inserted into bone and tension is placed on the suture. The tension on the suture causes the mid-section of the flexible anchor to rise, bunch, and compress into the cancellous bone to secure the anchor.
U.S. Patent Application No. 2013/0131722 to Marchand et al. discloses a soft suture anchor wherein the free ends of the suture enter and exit a sleeve member, and the suture passes one or more times through the interior and exterior of the sleeve member. The sleeve member is substantially hollow, and is formed by braiding. Marchand et al. disclose the use of surface coatings of hydroxyapatite powder or tricalcium phosphate on the sleeve to allow bone ingrowth. U.S. Patent Application No. 2012/0290004 to Lombardo et al. discloses a soft suture anchor comprising a fibrous construct and at least one suture, wherein the suture passes through the fibrous construct in at least three locations. U.S. Patent Application No. 2013/0018416 to Lombardo et al. discloses soft suture anchors made of braided or monofilament suture.
Smith and Nephew (Mass. USA) recently launched the SUTUREFIX ULTRA® device, which allows the soft anchor to form a ball against the inserter tube rather than the cortical layer of bone. However, the anchor still deploys laterally in a pre-drilled hole, forming a ball that provides sufficient compression for fixation (see: Smith & Nephew, Suturefix Ultra Brochure 00496 V 1, March 2014).
The soft suture anchors offer a number of advantages over conventional suture anchors. They are designed to reduce or eliminate bone loss following implantation, and can often be inserted into smaller bone holes minimizing damage to healthy tissue. The soft suture anchors also eliminate any hardware related issues by replacing the anchor component with a soft strand of suture material and a braid or a combination of a suture strand and a surrounding sleeve. Importantly, the soft suture anchors eliminate the possibility of loose pieces of anchor material getting into the joint if there is any breakage of the anchor.
To further improve the performance of soft suture anchors, it would be desirable to identify materials that can be used to improve the osteointegration of soft suture anchors. It would also be desirable to identify soft suture anchors where at least the anchor component is made from a resorbable composition that improves osteointegration, and more particularly where the anchor is completely replaced by bone following implantation. In addition, it would be desirable to identify a range of compositions such that the resorption rate of the anchor can be tailored to the tissue healing, and wherein the metabolites released during degradation do not cause inflammatory responses and are not highly acidic. Furthermore, it would be desirable to identify new anchor designs with higher pullout strengths, or that allow smaller bone holes to be used.
It is an object of the present invention to provide compositions and materials that can be used to improve the osteointegration of soft suture anchors.
It is another object of the invention to provide methods for manufacturing soft suture anchors that can be used to improve the osteointegration of soft suture anchors.
It is a further object of the invention to provide soft suture anchors manufactured from compositions and materials that can be used to improve the osteointegration of soft suture anchors.
It is still another object of the invention to provide methods for manufacturing the anchor component of a soft suture anchor from bioceramics, resorbable materials, and combinations thereof.
It is yet another object of the invention to provide soft suture anchors wherein the anchors have been manufactured from bioceramics, resorbable materials, and combinations thereof.
It is still further an object of the invention to provide soft suture anchors wherein the anchors have been manufactured from resorbable ceramics and resorbable polymers.
It is yet still another object of the invention to provide soft suture anchors with new anchors designs that provide higher pullout strengths and that can be used with smaller bone holes.